Chronic orofacial pain is a relatively common, poorly understood condition that lacks definitive diagnostic methods, prognostic models, or efficacious treatment. Recently, quantitative sensory testing (QST) of spinal and trigeminal nerves has been shown to help elucidate the mechanisms of pain conditions, and possibly shed light on the diagnosis, etiology, treatment and prognosis. Unfortunately, investigators working at different sites around the world use varying techniques, methodologies, and equipment to evaluate the somatosensory function of these nerves, and protocols are time consuming enough that they rarely can be used clinically, outside of research studies. Recently, the 10 centers of the German Research Network on Neuropathic Pain (DFNS) launched an ambitious initiative to standardize a feasible yet comprehensive protocol of QST for a specific region on the external body surface. This protocol can give a complete somatosensory profile of the nerve function of that region with 7 tests and 13 parameters within 30 min. Results are reported in an easy to view figure, showing neural hyper- or hypo-function in any one of the 13 parameters. In addition, enough data have been collected to yield normative values, and ongoing work in neuropathic pain conditions is likely to show known mechanisms linked to specific somatosensory profiles, thereby relating basic neural function with clinical signs and symptoms. We propose to build and extend this German protocol for intraoral regions, thereby creating a standardized, reliable battery of tests that can characterize the somatosensory profile of this anatomic area. Such a QST battery would open the door to international collaborative research efforts both within orofacial pain groups, and with cross-disciplinary groups such as the German Research Network. The clinical sites will be in Seattle, Washington;Aarhus, Denmark;and Malmo, Sweden. (Initial training has been completed in Mainz, Germany, and the intraoral training will be conducted in Seattle, Washington.) The remaining specific aims are: 2) Adapt the German QST protocol of external skin surfaces to intraoral regions, measure reliability;and 3) Conduct initial multi-national intraoral QST testing, including: a) the measurement of reliability of standardized sensory profile on patients with chronic persistent orofacial pain;b) determine the initial accuracy of QST measures differentiating intraoral persistent pain from controls;and c) Plan multi-national, large scale research projects to confirm the reliability, validity and utility of intraoral QST profiles and provide guidelines for their use. The long-term goal is to use the QST tools developed through this research to provide evidence-based criteria and methods to improve the differential diagnosis, classification, prognostic prediction and treatment of chronic, persistent, intra- and extra-oral pain. Project Narrative: Chronic pain in the face and mouth are relatively common conditions, and often have a devastatingly negative impact on the individual. This research aims to modify nerve testing protocols used on external body surfaces to evaluate pain condition inside the mouth. We anticipate that these adapted inside the mouth protocols will aid in the diagnosis and treatment of chronic orofacial pain.